Implements a StyleProcessor class to allow access to a list of set styles for a widget in String format. by neilcabanilla · Pull Request #2392 · eclipse-platform/eclipse.platform.swt

neilcabanilla · 2025-08-08T03:59:34Z

This PR allows us to fix issues with the CSS Spy in Eclipse PDE, detailed in Issue #611 Completed with @WillPeltz

Changes
-StyleProcessor class
Parses styles that can be set based on context, checks relevant styles against integer bitmask to see which are actually set, and converts them into String list

-getStyles method in Text and Button classes
Returns a list of styles currently set for a given widget in String format, allowing for style inspection at runtime

-Static function using instance of StyleProcessor in Text and Button classes
Clearly defines which styles can be set for a widget based on context, in a human-readable way.

Motivation

Currently, there is no built-in way to view a widget’s set styles in a human-readable format, leading to projects like Eclipse PDE implementing complex and limited parsers for UI elements like the CSS Spy tool. This PR makes this process much simpler and easier, without requiring much upkeep. It should be quite simple to add support for and update widget classes.

Notes
-Since this implementation only focuses on Text and Button classes, other widget classes should be revised incrementally to use the StyleProcessor class.

-Backwards compatible; existing behavior is unchanged.
Having both getStyles and checkStyle is a bit redundant, so merging them at some point in the future might be a good idea if it can be done without breaking existing behavior too much in downstream projects.

merks

Given the implementation details I see, could this not all be done externally without introducing APIs in SWT?

merks · 2025-08-08T06:55:32Z

+ * @return ArrayList<String> styles
+ * @since 3.131
+ */
+public ArrayList<String> getStyles() {


One would never want to surface the List implementation class in any API; elsewhere too.

Hello @merks,

Answering to your question...

Given the implementation details I see, could this not all be done externally without introducing APIs in SWT?

We initially explored other approaches such as implementing it in a utility class or using annotations, however based on the comments and guidance that we got Issue #611. We were advised to directly change the SWT repository, specifically the widget classes instead. That being said, we are flexible and happy to revise the implementation.

One would never want to surface the List implementation class in any API; elsewhere too.

You are right with what you've said. My teammate and I are planning to change this ArrayList to List instead and avoiding making the method public. We've only did it this way for testing purposes to see if it works and get feedback.

Thank you so much!
Teammate - @WillPeltz

merks · 2025-08-08T06:58:39Z

+
+import org.eclipse.swt.*;
+
+public class StyleProcessor {


Will this really become public API or can it just be package protected?

Hello @merks,

You're absolutely right, we actually intended for StyleProcessor to be package private, so that it can only be accessed within the widgets package. My teammate and I forgot that part, thank you for clarifying.

Thank you so much!
Teammate - @WillPeltz

laeubi · 2025-08-08T08:40:27Z

The recommendation was to access this reflectively and not to make any public API here.

WillPeltz · 2025-08-19T05:11:33Z

Hi @laeubi @merks,

Just wanted to follow up on our PR. @neilcabanilla and I took your feedback and made some fixes, so we would really appreciate if you could take another look when you have the chance. Thank you for your time.

getStyles(). # Conflicts: # bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Button.java # bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Text.java

Copilot

Pull request overview

This pull request introduces a new StyleProcessor utility intended to turn a widget’s integer style bitmask into a human-readable List<String> of active SWT style names, to support runtime style inspection (e.g., Eclipse PDE CSS Spy).

Changes:

Added a Win32-local StyleProcessor class that defines “one-of” and “some-of” style rules and evaluates them against a widget’s style bitmask.
Added Win32-only getStyles() methods to Text and Button that return the processed style names.
Added static STYLE_PROCESSOR configurations in Text and Button to describe which styles are relevant per widget/context.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

File	Description
bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Text.java	Adds a Win32 `STYLE_PROCESSOR` configuration and a `getStyles()` accessor for Text styles.
bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Button.java	Adds a Win32 `STYLE_PROCESSOR` configuration and a `getStyles()` accessor for Button styles.
bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/StyleProcessor.java	Introduces the `StyleProcessor` rule engine used to produce a String list of active SWT style constants.

Comments suppressed due to low confidence (4)

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/StyleProcessor.java:93

Avoid writing to stdout from SWT library code and avoid silently continuing after a programmer error. These style names are compile-time constants, so an invalid field should fail fast (e.g., throw IllegalArgumentException).

	    for (String s : someOfArr) {
	        try {
	            if ((style & SWT.class.getField(s).getInt(null)) != 0) {
	                finalList.add(s);
	            }
	        } catch (NoSuchFieldException | IllegalAccessException e) {
	            System.out.println("Invalid Style: " + s);
	        }

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/StyleProcessor.java:108

Avoid writing to stdout from SWT library code and avoid silently continuing after a programmer error. If a condition style constant is invalid, fail fast so the bad rule definition is caught during development.

	            try {
	                int flag = SWT.class.getField(condition).getInt(null);
	                if ((style & flag) != 0) {
	                    matched = true;
	                    break;
	                }
	            } catch (NoSuchFieldException | IllegalAccessException e) {
	                System.out.println("Invalid condition: " + condition);
	            }

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/StyleProcessor.java:121

Avoid writing to stdout from SWT library code and avoid silently continuing after a programmer error. If a thenOneOf style constant is invalid, fail fast.

	                try {
	                    int flag = SWT.class.getField(s).getInt(null);
	                    if ((style & flag) != 0) {
	                        finalList.add(s);
	                        break;
	                    }
	                } catch (NoSuchFieldException | IllegalAccessException e) {
	                    System.out.println("Invalid thenOneOf: " + s);
	                }

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/StyleProcessor.java:132

Avoid writing to stdout from SWT library code and avoid silently continuing after a programmer error. Also, remove the extra trailing semicolon.

	                try {
	                    int flag = SWT.class.getField(s).getInt(null);
	                    if ((style & flag) != 0) {
	                        finalList.add(s);
	                    }
	                } catch (NoSuchFieldException | IllegalAccessException e) {
	                    System.out.println("Invalid thenSomeOf: " + s);;
	                }

+}
+
 static int checkStyle (int style) {
+	System.out.println(STYLE_PROCESSOR.process(style));


 package org.eclipse.swt.widgets;
-
-
+import java.util.List;
 import java.util.*;



 package org.eclipse.swt.widgets;
-
+import java.util.List;
+import java.util.*;



+List<String> getStyles() {
+	return STYLE_PROCESSOR.process(this.style);
+}


+List<String> getStyles() {
+	return STYLE_PROCESSOR.process(this.style);
 }


+		        } catch (NoSuchFieldException | IllegalAccessException e) {
+		            System.out.println("Invalid Style: " + s);
+		        }


github-actions · 2026-07-28T15:59:01Z

Test Results (win32)

33 files ±0 33 suites ±0 4m 49s ⏱️ -27s
4 861 tests ±0 4 785 ✅ ±0 76 💤 ±0 0 ❌ ±0
1 390 runs ±0 1 366 ✅ ±0 24 💤 ±0 0 ❌ ±0

Results for commit 31e6c5f. ± Comparison against base commit 7b3acfd.

merks reviewed Aug 8, 2025

View reviewed changes

neilcabanilla and others added 11 commits July 28, 2026 18:40

Started working on the StyleProcessor class and the methods for it.

814af64

Added print statements to the catch method in StyleProcessor.

6632c74

Modified styleProcessor to use rule class, added thenSomeOf

13e86c0

Tentative text class implementation of styleProcessor

4b20eb7

Added someOf method for non-mutually-exclusive checks, used to fix text

96a7e8d

Changed the process method in StyleProcees w/ @WillPeltz

e05320b

Removed the StackTrace in the catch block (process method) w/ @WillPeltz

6148f6f

Removed the public keywords & changed to package-private.

14d2203

Removed the comments on getStyles for Text & Button

ea8466a

Fixed error w/ @WillPeltz of NoSuchMethod in Text class, not showing

e2fc41c

getStyles(). # Conflicts: # bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Button.java # bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Text.java

FIx error regarding, "Graphic is disposed" w/ WillPeltz

31e6c5f

akurtakov force-pushed the processor branch from 34a0672 to 31e6c5f Compare July 28, 2026 15:41

akurtakov requested a review from Copilot July 28, 2026 15:46

Copilot started reviewing on behalf of akurtakov July 28, 2026 15:46 View session

Copilot AI reviewed Jul 28, 2026

View reviewed changes

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Implements a StyleProcessor class to allow access to a list of set styles for a widget in String format. - #2392

Implements a StyleProcessor class to allow access to a list of set styles for a widget in String format.#2392
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